Kent police announced the charges as more detail came to light about the attack, which has prompted an outpouring of concern in Italy.

A source close to the Italian embassy in London said there was huge political pressure from Rome to get to the bottom of the incident following reports in the Italian press that Leotta was the victim of a racially motivated attack.

Claudio Usuelli, the mayor of Nibionno, Leotta's home town in the northern region of Lombardy near Milan, told the Italian news agency Ansa that the community had been left shocked by the killing.

Usuelli said informed sources had told them that the attackers had "broken down the door of their room, yelling, 'Italian crap, you're stealing our jobs.'"

However, that theory was quickly snuffed out by detectives in Kent, who said the killing was "not a racially aggravated murder" or in connection with a dispute over jobs.

A Kent police spokesman refused to be drawn on suggestions that detectives were considering the possibility that Leotta and his friend were victims of mistaken identity.

The man's father, Ivan Leotta, was quoted as saying in the Italian newspaper Corriere della Sera: "I know the other boy attacked, but he's still in shock after the beating he suffered. I don't think he had time to get into any sort of trouble."

Leotta is understood to have arrived in Kent with his friend, Galbiati, this month and was trying to learn English. The families of both men have flown to the UK and are receiving consular support.

Police were first called to reports of an assault above Vesuvius Italian restaurant, where Leotta worked, on Sunday evening. Seven men were arrested in the immediate aftermath, police said.

Leotta was taken to King's College hospital in London, but later died from a number of serious head and chest injuries.

Galbiati and one of the police suspects were taken to a nearby hospital with injuries but both were later released.

Three suspects had been released on police bail, police said on Wednesday, while one man had been released without charge and two men remained in police custody.

A Facebook page set up in Leotta's memory has received hundreds of tributes. One posting, from Thomas Manzo, read: "Rest in peace piccolo … looking for a better life and have found only hatred … There are no words to describe [who did this to you]."